Dowel bar loader

ABSTRACT

A dowel bar loader comprising an inlet for receiving dowel bars, an outlet for delivering dowel bars, and a serpentine path connecting the inlet to the outlet. The path includes at least three changes in direction between the inlet and the outlet. In preferred embodiments, the path can include seven changes in direction or more. In one embodiment, the changes in direction comprises an angle change of at least about twenty-five degrees. The dowel bar loader further includes a control mechanism positioned to control movement of dowel bars in the path, and a spacer mechanism for spacing the dowel bars from each other in preparation for delivery to the dowel bar inserter. Preferably, the control mechanism is upstream of the spacer mechanism and spaced from the outlet. In one embodiment, the control mechanism comprises a control wheel that rotates completely around during normal operation.

BACKGROUND

The present invention relates generally to the field of concrete paving, and more specifically to a dowel bar loader that provides dowel bars to a concrete paver.

Concrete slipform pavers are used to create concrete slabs to form load-bearing surfaces, such as roads. Such pavers commonly include a tractor that moves a slipform over freshly-laid concrete to create a smooth slab of concrete.

In the process of forming concrete slabs, it is often desired to provide reinforcement to the concrete at certain locations, such as the joints between adjacent slabs. This is typically done by embedding dowel bars across the location of the joint. In order to facilitate the insertion of dowel bars, mechanisms called dowel bar inserters are commonly attached to the slipform pavers and are designed to insert the dowel bars into the freshly-laid concrete. An example of a dowel bar inserter is disclosed in U.S. Pat. No. 6,390,726, which is incorporated herein by reference in its entirety.

Dowel bar inserters must be provided with a supply of dowel bars. This is commonly done manually by having a worker positioned near the side of the dowel bar inserter and next to a supply of dowel bars. The worker must periodically load the dowel bars into the dowel bar inserter. This process can be very slow, and can limit the speed of the entire concrete paver.

In order to remedy this problem, mechanisms called dowel bar loaders can be used to load the dowel bars into dowel bar inserters. Dowel bar loaders are commonly mounted to the dowel bar inserters, and provide a faster way to load dowel bars into a dowel bar inserter. Some dowel bar loaders are very complex and expensive mechanisms, and can cause mechanical malfunctions, such as jamming of dowel bars.

SUMMARY

The present invention provides a dowel bar loader that effectively loads dowel bars into a dowel bar inserter. In one embodiment, the dowel bar loader comprises an inlet for receiving dowel bars, an outlet for delivering dowel bars (e.g., to the dowel bar inserter), and a serpentine path connecting the inlet to the outlet. The serpentine path includes at least three changes in direction between the inlet and the outlet. In preferred embodiments, the path can include as many as seven changes in direction, or more. In one embodiment, the changes in direction comprises an angle change of at least about twenty-five degrees, preferably at least about thirty-five degrees, and more preferably at least about forty-five degrees.

In another aspect of the invention, the dowel bar loader further includes a control mechanism positioned to control movement of dowel bars in the path, and a spacer mechanism for spacing the dowel bars from each other in preparation for delivery to the dowel bar inserter. Preferably, the control mechanism is upstream of the spacer mechanism and spaced from the outlet.

In one embodiment, the control mechanism comprises a control sprocket having multiple fingers, at least one of the fingers being positioned at least partially in the path. Preferably, the control sprocket rotates completely around during normal operation. The control mechanism can also include a detent mechanism for stopping movement of dowel bars in the path.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial exploded view of a dowel bar loader embodying the present invention coupled with a prior art dowel bar inserter.

FIG. 2 is an enlarged rear perspective view of the dowel bar loader of FIG. 1.

FIG. 3 is an enlarged perspective view of the dowel bar loader of FIG. 1.

FIG. 4 is a front view of the dowel bar loader of FIG. 1.

FIG. 5 is a side view of the dowel bar loader of FIG. 1.

FIG. 6 is a section view taken along line 6-6 in FIG. 4.

FIG. 7 is a section view taken along line 7-7 in FIG. 4.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, unless otherwise noted, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

FIG. 1 illustrates a dowel bar loader 10 embodying the present invention exploded off the side of a dowel bar inserter 12. The illustrated dowel bar inserter 12 is manufactured and sold by Guntert & Zimmerman. The dowel bar inserter 12 is mounted to the main frame 14 of a concrete paver and includes a carriage 16 that is designed to move relative to the main frame 14, toward and away from the paver. When the dowel bar inserter 12 is inserting dowel bars 26 in the concrete (the “inserting operation”), the carriage 16 is moving relative to the main frame 14 and is substantially stationary relative to the laid concrete. When the dowel bar inserter 12 is being loaded with dowel bars 26 (the “loading operation”), it is substantially stationary relative to the main frame 14 and in the loading position shown in FIG. 1.

The carriage 16 includes a loading section having two opposing chains 20 that each includes a plurality of flights 22. The flights 22 on one chain are in opposing relations to flights 22 on the other chain, and the chains 20 are driven synchronously such that each pair of flights 22 defines a pocket 24 (see FIG. 5) into which a dowel bar 26 can be loaded. The pockets 24 are spaced from each other by a pitch P (see FIG. 5). In this loading section, the chains 20 are vertically positioned such that the pockets 24 are vertically oriented relative to each other.

The dowel bar loader 10 is mounted to the carriage 16 adjacent to the chain-driven flights 22 such that dowel bars 26 in the dowel bar loader 10 can be loaded into the pockets 24. The dowel bar loader 10 includes two side plates 28, two guide plates 30, a lower shaft 32 extending through all four plates, and an upper shaft 34 extending through all four plates. Each side plate 28 is coupled with a corresponding guide plate 30 by four connecting plates 36. A mounting flange 38 is secured to the outer surface of each side plate 28 to facilitate securing the dowel bar loader 10 to the carriage 16 of the dowel bar inserter 12.

With reference to FIG. 3, each guide plate 30 includes a serpentine slot 40 from an inlet 42 at the top of the plate to an outlet 44 at the bottom of the plate. Because each slot 40 extends all the way through the corresponding guide plate 30, each guide plate 30 actually comprises two distinct plates that cooperatively define the slot 40. The slot 40 is sized to allow the dowel bars 26 to be inserted at the inlet 42 and slide down the slot 40 toward the outlet 44.

Referring to FIG. 6, the slot 40 defines a path having upstream and downstream directions defined by the inlet 42 and outlet 44, respectively. The path changes direction several times between the inlet 42 and the outlet 44. More specifically, the illustrated path changes directions at least seven times, which each change of direction occurring at a corner C. At each corner, the change in direction δ is about forty-five degrees.

A control mechanism in the form of a pair of control sprockets 50 is secured to the upper shaft 34 between the two guide plates 30 and spaced upstream from the outlet 44. Each control sprocket 50 rotates with the upper shaft 34 in a single direction during normal operation. The control sprocket 50 includes seven fingers 52 defining seven cavities 54 that are each sized to accommodate a dowel bar 26. As shown in FIG. 6, the fingers 52 of the control sprockets 50 extend into the slot 40 such that the fingers 52 will engage a dowel bar 26 sliding down the slot 40. In other embodiments, the control mechanism may be a control wheel or another mechanism, as desired.

Referring to FIG. 3, a detent mechanism in the form of a detent member 60 is secured to the upper shaft 34 on the outside of one of the side plates 28. The detent member 60 rotates with the upper shaft 34 and includes multiple notches 62. A latch member 64 is pivotally attached to the side plate adjacent the detent member 60 and is movable between a latched position, where the upper shaft 34 and control sprockets 50 are prevented from rotating, and an unlatched position, where the upper shaft 34 and control sprockets 50 are allowed to rotate. In this manner, the passage of dowel bars 26 through the slot 40 can be controlled, as described below in more detail. An actuator in the form of a solenoid 66, is coupled to the latch member 64 for movement between the latched and unlatched positions. It should be understood that the illustrated detent member 60 and latch member 64 is one way of controlling the movement of the dowel bars 26 in the slot 40, but other mechanisms are possible.

With further reference to FIG. 6, a spacer mechanism in the form of a pair of spacer sprockets 70 is positioned downstream of the control mechanism and near the outlet 44. The spacer sprockets 70 are secured to the lower shaft 32 outboard of the guide plates 30 and inboard of the side plates 28 (see FIG. 4). Each spacer sprocket 70 rotates with the lower shaft 32 and includes six spacers 72 defining six recesses 74 that are sized to receive a dowel bar 26. As shown in FIG. 6, the spacers 72 of the spacer sprocket 70 extend into the slot 40 such that the spacers 72 will engage a dowel bar 26 sliding down the slot 40. The spacers 72 are dimensioned so that the recesses 74 are spaced from each other by a distance D (FIG. 7) that approximately corresponds with the pitch P (FIG. 5) of the pockets 24 on the dowel bar inserter 12. This feature facilitates spacing of the dowel bars 26 for proper insertion into the pockets 24. In other embodiments, the spacer mechanism may be a spacer wheel or another mechanism, as desired.

Referring to FIGS. 1 and 2, a dowel bar hopper 80 is pivotally mounted to the main frame 14 at a pivot shaft 82. The hopper 80 is manually pivotable about the pivot shaft 82 between a loading position (shown in FIGS. 1 and 2) and an unloading position (rotated slightly clockwise in FIG. 1 and counter-clockwise in FIG. 2). The illustrated hopper 80 is biased by gravity toward the loading position into contact with the main frame 14. The hopper 80 is designed to be filled with dowel bars 26 in preparation for providing dowel bars 26 to the dowel bar loader 10.

A dowel bar chute 90 (FIG. 1) is mounted to the main frame 14 and is aligned with the hopper 80. The chute 90 is designed to receive dowel bars 26 from the hopper 80 (when the hopper 80 is in the unloading position) and deliver the dowel bars 26 by gravity to the top of the dowel bar loader 10.

In operation, dowel bars 26 are inserted into the hopper 80 in the loading position in preparation for delivery to the dowel bar loader 10. Typically, insertion of the dowel bars 26 into the hopper 80 would be done manually while the dowel bar inserter 12 is performing the inserting operation. Because the hopper 80 is fixed to the main frame 14, it is stationary relative to the main frame 14 at all times, which facilitates loading of the hopper 80 by a worker sitting on the main frame 14. Preferably, the precise number of dowel bars 26 needed for a single inserting operation is loaded into the hopper 80.

After the previous inserting operation is completed, the carriage 16 of the dowel bar loader 10 returns to the loading position, where it will stay for a period of time. While in the loading position, the worker moves the hopper 80 to the unloading position, which causes the dowel bars 26 to fall onto the chute 90 and move by gravity toward the inlet 42 of the dowel bar loader 10. The dowel bars 26 will travel down the slot 40 until the first dowel bar 26 reaches the control sprocket 50, where it will be held due to the engagement of the latch member 64 with the detent member 60.

When it is desired to load the dowel bars 26 into the dowel bar inserter 12, the worker moves the latch member 64 to the unlatched position (e.g., by pushing a button to actuate the solenoid 66), which allows the control sprockets 50 to rotate and allows the dowel bars 26 to continue sliding down the slot 40. The first dowel bar 26 will enter a recess between two spacers 72 on the spacer sprockets 70. Gravity will cause the spacer sprockets 70 to rotate, thus allowing the dowel bar 26 to move toward and into a pocket 24 of the dowel bar inserter 12. As the chain of the dowel bar inserter 12 is moved, the next pocket 24 of the dowel bar inserter 12 is aligned with the spacer wheel, and the next dowel bar 26 in the slot 40 will move into that pocket 24 by gravity. It is noted that the spacers 72 maintain a proper spacing of the dowel bars 26 such that the dowel bars 26 fall easily into the pockets 24 of the dowel bar inserter 12. This process continues until each of the pockets 24 of the dowel bar inserter 12 is provided with a dowel bar 26. The dowel bar inserter 12 then inserts the dowel bars 26 into the laid concrete, as is generally known in the art.

Thus, the invention provides, among other things, a dowel bar hopper 80, chute 90, and loader that facilitates loading of dowel bars 26 into a dowel bar inserter 12. Various features and advantages of the invention are set forth in the following claims. 

1. A dowel bar loader adapted to provide dowel bars to a dowel bar inserter, the loader comprising: an inlet for receiving dowel bars; an outlet for delivering dowel bars; and a serpentine path connecting the inlet to the outlet, the serpentine path including at least three changes in direction between the inlet and the outlet.
 2. A dowel bar loader as claimed in claim 1, wherein the path includes at least four changes in direction between the inlet and the outlet.
 3. A dowel bar loader as claimed in claim 1, wherein the path includes at least five changes in direction between the inlet and the outlet.
 4. A dowel bar loader as claimed in claim 1, wherein the path includes at least six changes in direction between the inlet and the outlet.
 5. A dowel bar loader as claimed in claim 1, wherein each of the changes in direction comprises an angle change of at least about twenty-five degrees.
 6. A dowel bar loader as claimed in claim 1, wherein each of the changes in direction comprises an angle change of at least about thirty-five degrees.
 7. A dowel bar loader as claimed in claim 1, wherein each of the changes in direction comprises an angle change of at least about forty-five degrees.
 8. A dowel bar loader as claimed in claim 1, further comprising a control mechanism positioned to control movement of dowel bars in the path.
 9. A dowel bar loader as claimed in claim 1, wherein the control mechanism comprises a control sprocket having multiple fingers, at least one of the fingers being positioned at least partially in the path.
 10. A dowel bar loader assembly adapted to provide dowel bars to a dowel bar inserter, the loader comprising: an inlet for receiving dowel bars; an outlet for delivering dowel bars; a path connecting the inlet to the outlet; a control mechanism for controlling the movement of dowel bars in the path; and a spacer mechanism for spacing the dowel bars from each other in preparation for delivery to the dowel bar inserter.
 11. A dowel bar loader as claimed in claim 10, wherein the inlet and outlet define upstream and downstream directions of the path, respectively, and where the control mechanism is upstream of the spacer mechanism.
 12. A dowel bar loader as claimed in claim 10, wherein the control mechanism includes a detent mechanism for stopping movement of dowel bars in the path.
 13. A dowel bar loader as claimed in claim 10, wherein the control mechanism comprises a control sprocket having multiple fingers, at least one of the fingers being positioned at least partially in the path.
 14. A dowel bar loader as claimed in claim 13, wherein the control sprocket rotates completely around during normal operation.
 15. A dowel bar loader as claimed in claim 10, wherein the control mechanism is spaced upstream from the outlet. 